Reticulating apparatus



April l, 1958 J. w. HILL.

RTICULATING APPARATUS '7 Sheets-Sheet 1 Filed March 8, 1952 .|\|\|||,|`l.||ri1w u, l|.|uHH f o! .Ill L` 3 QH o.n\ QH\ 6 mi IIH\ 2 illnl IIN Wllil .l 3 l W1 l.; w/w3. HIM WU .my VH1 .m l l1( Q |lH w Q l\| \|1l u ,N M1 |\|hli|\||\|\| ll Mm. WW ml .uml MMI. um Ml l d@ W11 2 w vk UUHll NHV ./n. www ,m T .I f1.4.. \9. @W @Wow Wow Hw M .Q N 5 2 April 1, 1958 J. W. HILL RETICULATING APPARATUS Filed March 8, 1952 '7 Sheets-Sheet 2 J. W. HILL RETICULATING APPARATUS April 1, 195s 7 Sheets-Sheet 5 Filed March 8, 1952 IN VEN TOR.

April 1, 195s J. w. HILL 2,828,792

RETICULATING APPARATUS Filed March 8. 1952 '7 Sheets-Sheet 4 .Mum

./KMZQ April 1, 1958 J. w. HILL. 2,828,792

RETICULATING APPARATUS Filed March 8, 1952 7 Sheets-Sheet 5 ai I HHN

A AAA A A MMM i M2M/Wr@ April l, 1958 J. w. HILL 2,828,792

RETICULATING APPARATUS Filed March 8, 1952 A 7 Sheetsheet 7 1NVENToR.

iinited States Fatent RETICULATING APPARATUS John W. Hill, Chicago, lll., assignor to The Globe Company, Chicago, Ill., a corporation of iiinois Application March 8, 1952, Serial No. 275,664

Claims. (Cl. 153-2) This invention relates to apparatus for making reticulated sheet material and has special reference to a slitting and punching machine for producing reticulated sheets with substantially diamond-shaped openings, of the type disclosed in my copending application Serial No. 251,088, filed October 12, 1951.

The machine of the present invention operates upon blanks of sheet material, such as steel or aluminum being fed therethrough. As a sheet progresses, the machine first slits the central portion thereof to form strips extending between and substantially at right angles to integral marginal flanges or edges and connected by rows of saddes or bonds running generally parallel to the marginal edges. The slitted portion is then attened to bring all parts thereof back into the original plane of the sheet. Thereafter punches are forced through the sheet from opposite sides to open the slits and rearrange the metal to form strips substantially normal to the plane of the sheet extending between the unslitted marginal flanges and shaped to provide substantially diamondshaped openings therebetween.

The blank is fed intermittently and positioning means are provided to insure that the sheet moves the same distance each time between operations thereby resulting in reticulated sheets that are uniform throughout. The side margins of the sheet are preferably maintained in the original plane of the sheet and substantially a xed distance apart during the passage of the blanks through the machine. The blanks also maintain substantially their original length throughout the reticulating operation.

An object of the present invention is to provide a machine for forming reticulated metal sheets of substantially the same size as the original blanks and having substantially diamond-shaped openings.

Another object is to provide a machine for forming reticulated sheets having a central reticulated portion and integral substantially longitudinally straight marginal edges outwardly of and on opposite sides of the reticulated portion.

A further object is to provide a reticulating machine for slitting the blank and thereafter rearranging the metal of the slitted portion to form substantially diamondshaped openings between transverse strips substantially normal to the plane of the sheet.

till another object is to provide a reticulating machine which holds the marginal edges of the blanks substantially a fixed distance apart during operations on the blank.

A still further object is to provide a reticulating machine having punches for forming diamond-shaped openings in the central portion of the blank and side holddown members for shaping the blank adjacent the outer punches.

Further objects and advantages will be apparent from the following description and claims when considered with'the accompanying drawings, in which Fig. l is a perspective view of a reticulating machine 2,828,792 Patented Apr. 1, 1958 "ine e embodying the present invention with portions thereof broken away;

Fig. 2 is a side elevational View of the slitting, flattening and punching portions of the machine shown in Fig. l;

Fig. 3 is a transverse vertical cross-sectional view taken on the line 3 3 of Fig. 2;

Fig. 4 is atop plan view of the lower die member taken on the line 4 4 of Fig. 2;

Fig. 5 is a bottom plan view of the upper die member taken on the line 5 5 of Fig. 2;

Fig. 6 is a longitudinal vertical cross-sectional View of the portion of the machine disclosed in Fig. 2 with the parts in changed position, taken generally along the line 6 6 of Fig. 4;

Fig. 7 is a top plan view of the slitted portion of a blank;

Fig. 8 is a top plan view of the reticulated portion of the sheet;

Fig. 9 is a cross-sectional view taken on the line 9 9 of Fig. 8;

Fig. 10 is a horizontal cross-sectional view of a modified form of locating mechanism for removing a marginal strip from the sheets being treated, to position exactly the sheets after each advance; and

Fig. ll is a vertical cross-sectional view taken on the line M ii of Fig. 10.

Referring more particularly to the drawings, there is shown a reticulating machine embodying the present invention intended for forming reticulated sheets having a central portion with substantially diamond-shaped `openings therein and integral marginal flanges extending longitudinally at opposite sides of the sheet.

The machine may comprise feeding means for intermittently feeding the blanks a predetermined distance, a slitting section for slitting the blank, a flattening section for flattening the slitted portions of the blank, and a punching section for rearranging the metal in the slitted, flattened portion of the blank to form strips substantially normal to the plane of the sheet extending between the unslitted marginal portions or flanges and shaped to provide substantially diamond-shaped openings therebetween. Y

The reticulating machine 1 is provided with upper and lower platens il and l2 respectively which preferably carry the various operating elements of the machine. The platens are arranged for relative movement toward and away from each other and may be mounted in a machine such as a punch press 1 in which the lower platen is stationary and the upper platen is vertically reciprocated by suitable power means. Such a machine is normally provided with a very heavy fly wheel to insure smooth operation.

An upper mounting plate 13 is secured to the lower face of the upper platen ll. by any suitable means such as screws or bolts, so that if desired, the upper mounting plate may be removed. A lower mounting plate 14 is secured to the upper surface of the lower platen l2 by similar securing means which permit its removal and replacement. The various slitting, attening, and punching or rearranging members may be secured to the opposed faces of the upper and lower mounting plates.

The slitting mechanism disclosed, is employed for forming transverse rows of overlapping slits as illustrated in Fig. 7. The slits in each row are arranged longitudinally of the row.

While any suitable slitting mechanism may be employed, that illustrated comprises a plurality of cooperating pairs of upper and lower cutting members. The upper `cutting members i5, 16, 17 and i8 extend transversely and are formed with spaced serrated cutting portions at the rear sides thereof, extending below the rest ofthe cutters, and

the lower cutting members 19, Ztl, 21 and 22 which cooperate respectively with the upper cutting members 15, 16, 17 and 13, are provided with cooperating serrated cutting portions at the upper rear sides thereof. In de* scribing the present machine, the receiving end is designated the front and the discharge end is designated the rear thereof. The serrated cutting portions of each pair of cooperating upper and lower cutting members mate so as to produce a serrated slit. While such a slit is preferable, the cutting members may also be formed to provide a straight or other suitably shaped slit. lt is to be noted that the cutting members 16 and 21 are fifty per cent wider than the adjacent cutting members. A supporting block 22a is located forwardly of the lower cutting member 22 and directly below the upper cutting member 18.

Suitable feeding means are employed for intermittently feeding the blanks of material, such as steel or aluminum sheets, through the machine. Such feeding mechanism may consist of a pair of intermittently operated feed rolls 23 which advance the sheets step by step through the machine. The rolls may be driven by any suitable mechanism. Other types of feeding means may also be employed for this purpose.

In order to form rows of overlapping slits, the cooperating cutting members 15, 19 and 16, 20 are each provided with one less cutting portion than the cutters 17, 21 and 18, 22 and are ollset therefrom as shown in Figs. 4 and 5.

The sheets may be fed at each step a distance equal to twice the distance between the cutting edges of the cutting members 17 and 18. The leading end of a sheet is rst fed into the machine a sufficient distance to permit these two cutting edges together with the cooperating edges of the members 21 and 22 to form two transverse rows of slits in the sheet. After the sheet has been advanced the required distance, the rst two rows of slits formed will lie on opposite sides of tie cutting edges of the cutting members 16 and 29. Thus, when the cutters are again operated, rows of overlapping slits will be formed on opposite sides of the row of slits just formed by the cutters 17 and 21, and the cutting edges of the cutting members 17, 21 and 18, 22 will form two more rows of equally spaced rows of similar slits. This will result in a slitted portion such as shown in Fig. 7. The cutting members 15, 18 and 19, 22 may be secured to their respective mounting plates by means of screws: 24. This permits ready removal of the cutters such as for sharpening or replacing.

Rearwardly of the cutting members there are cooperating ilattening members 25 and 26, secured to the opposed faces of the mounting plates by screws 27a or other suitable securing means. The rear edges of the flattening members 25 and 2o are similarly notched or serrated as shown particularly in Figs. 4 and 5. The projecting portions 26a at the rear of the flattening members are aligned longitudinally of the machine with the center of the slits in the longer rows produced by the cutters 17, 21 and 18, 22 and the notches or depressions therebetween are similarly aligned with the center of the slits in the shorter rows produced by the cutters 15, 19 and 16, 20. As the slitted portions of the sheets pass between the opposed llat surfaces of the flattening members 2S and 26, the portions offset from the surfaces of the sheet by the cutters are restored to their original position and all portions of the sheet again lie between the original upper and lower surfaces thereof.

Rearwardly of the flattening members there are a plurality of opening members, such as punches, whose function is to rearrange the metal to produce a reticulated sheet of the type illustrated in Figs. 8 and 9. The punches are arranged in upper and lower sets, the upper set being secured to the upper mounting plate 13 and extending Y downwardly therefrom, and the lowerpunches being se- Acured to the lower mounting plate 14 and extending upwardly therefrom. A plurality of transverse rows of upper and lower punches are preferably employed.

As shown in Fig. 4, the lower mounting plate 14 may be provided with four transverse rows of punches 27 and 28, with the punches in each row equal in number to and arranged to engage the slits in one of the longer rows. For purposes of illustration four punches are employed in each row on the lower platen 14. It has been found preferable to employ one or more rows of relatively narrow punches 27, which rst enter the slits. Thus, the slits in two alternate rows will first be partially opened by the punches 27 and thereafter will be completely opened by the punches 28. All the lower punches are substantially diamond-shaped in cross-section and taper from a relatively sharp upper edge downwardly and outwardly therefrom as shown in Figs. 1-5. However, it has been found desirable to make one side of the punches 27 ilatter than the other.

The upper set of punches carried by the upper mounting plate 13 (Fig. 5) includes one more row of punches with one less punch in each longitudinal row than the lower set of punches. The punches 30a in the tirst few rows are preferably of substantially the same size and shape as the narrow punches 27, and the wider upper punches 3i) in the other rows are like the punches 28. The upper punches are positioned so that the first row will lie forwardly of the llrst row of lower punches, the last row will be to the rear of the last bottom row, and the other rows of upper punches will be intermediate the rows of lower punches. The upper punches are also offset longitudinally of their long dimensions from the lower punches so that they are aligned longitudinally of the machine with the slits in the shorter rows formed by the cutters 15, 19 and 16, 20. Moreover, the upper row of punches toward the front or receiving end of the machine will be adjacent the notches in the lower flattening plate 26. This position may be seen from Fig. 5 as the rear notched edges of the flattening plates 25 and 26 are vertically aligned. The sheet is therefore supported adjacent the front row of upper punches.

The rearranging of the metal in the sheet is accomplished by the punches without any substantial drawing of the metal. The metal adjacent the slits is bent upwardly or downwardly from the plane of the sheet and the resulting strips which are substantially normal to the plane of the sheet are shaped to form diamond-shaped openings therebetween, as shown in Fig. 8.

During the advance of the sheets through the machine they are supported by longitudinally arranged supporting bars or plates 31 and 32 at each side of the machine. The plate 31 may be provided with a Vertical flange 31a along its outer side which serves as a guide for the sheets. The supporting plates 31 and 32 have guide pins 33 fixed to the lower sides thereof, which are vertically slidable in openings provided therefor in the lower mounting plate 1d and the lower platen 12. Additional guide pins 34 also fixed to the lower side of the supporting member 32 slide in openings provided therefor in the lower platen 12. Nuts 3S or other enlarged heads are secured to the lower ends of the pins 33 and 34 and serve to limit their upper movement.

Compression springs 36 are positioned intermediate the pins 33 between the suporting pla-tes 31 and 32 and the lower mounting plate 14. The springs 36 normally maintain the supporting plates 31 and 32 in their upper position, as illustrated in Fig. 3. Additional springs 37 are located intermediate the pins 34 between the supporting member 32 and the lower platen 12, and also serve to normally maintain the supporting plate 32 in its upper position.

Longitudinally extending clamping plates 38 and 39 carried by the upper platen 11 are positioned directly above and cooperate with the supporting plates 31 and 32. These clamping plates are supported by pins 41 and 42. The lower ends of the pins 41 are xed to the clamping plate 38 and their upper ends are slidably mounted in holes provided in the upper platen 11. Similarly, the pins 42 are fixed at their lower ends to the clamping plate 39 and their upper ends are slidable in openings provided in the upper platen 11. Suitable means are employed to limit the downward movement of the pins. Springs 43 are positioned about the pins 41 and 42 between the clamping plates 38 and 39 and the upper platen 11. The springs 43 normally maintain the clamping plates 33 and 39 in lower position, preferably with their lower surfaces below or substantially horizontally aligned with the ends of the punches 3i) and 36a as illustrated in Fig. 3.

Also carried by the upper platen 11 are a plurality of hold-down fingers 44, which extend downwardly from supporting bars 45. Pins 46 having their upper ends slidable in platen 11 support the bars 45. Springs 47 positioned between the platen 11 and the supporting bars 45 normally hold the bars in their lower position with the free ends of the hold-down lingers 44, preferably substantially horizontally aligned with the ends of the punches 30 and 39a. Means are also provided to limit the downward movement of the supporting bars 45. With this construction, when the upper platen is moved downwardly, the clamping plates 38 and 39, the hold-down ngers 44 and the punches 30 and 30a will all engage the blank supported on the supporting plates 3l and 32 at about the same time.

The hold-down lingers are each substantially triangular in cross-section with the base facing outwardly and the apex rounded and facing inwardly (Fig. 5). Moreover, the lower faces slope downwardly from the outer sides to the inner apices (Fig. 3). A linger is preferably positioned at each end of the rows of upper punches 3l) and 38a, as illustrated in Fig. 5. When the upper platen 11 is moved downwardly, these lingers will engage the blank on the front and rear sides of the end punches 27 and 28 in each row, thus counteraoting the upward force on the sheet of the lower punches at the end of the rows, and at the same time forcing the portions of the sheet engaged thereby downwardly below the plane of the sheet, as indicated at 44a in Fig. 9.

Guide rods 4S secured to the platen 1l and movable in openings therefor in the lower platen 12, serve to guide the upper platen 11 during its movement.

ln order rto produce uniform reticulated sheets, it is essential that the blank be moved the same distance each time. This may be accomplished-by means of a punch 51 on the lower side of the clamping plate 38 (Fig. 2) which punches an opening 5@ in the margin of the blank at each actuation of the upper platen 11. The supporting member 31 is provided with a cooperating opening 52 into which the punch 5l fits. This portion of the supporting plate 31 acts as a lower cutting die.

Pins 53 are mounted on the lower side of the clamping plate 38 throughout its length. The pins and the punch 5l are spaced on centers a distance equal to that of the desired movement of the blank. Mating openings 52a are also provided in the lower supporting plate 31 for each of the pins 53. Thus, after each operation of the machine the sheet is moved forward the exact distance desired, as the pins engage the openings in the sheet to accomplish this result.

Referring to Figs. l0 and l1, there is shown a modified form of locating mechanism for exactly positioning the sheets after each advance. ln this form the supporting plate 3l is provided with a punch and die construction adjacent the cutting members, and the flange 31a at the receiving end of the machine is removed. A die 60 provided with cutting edge 61 at the other side thereof supports one side of the sheet adjacent the cutters. This die cooperates with a vertically movable punch 62 preferably mounted on the lower side of the clamping plate 6 38. The punch 62 is of a length equal to the desired advance of the sheet.

The supporting plate 32 may be provided with a guide flange 32a for maintaining the sheet in position between it and a guide tlange 63 on the die 60. The sheet to be processed is initially of a width equal to the distance between the guide flanges 32a and 63, and the punch 62 removes a strip from the edge of the sheet to be processed in widthl equal to the difference in distance between the guide flanges 32a and 63 on one hand, and 32a and 31a on the other, and of a length equal to the desired distance of advance of the sheet.

The sheet is advanced between the flanges 32a and 63 until it engages the forward end of the flange 31a. The punch 32 is then moved downwardly with the upper clamping plate 38 and removes a rectangular strip of the size indicated from the edge of the sheet. When the upper clamping plate 38 is raised, the sheet is again advanced until the shoulder at the wide part of the sheet again engages the flange 31a.

In the operation of the reticulating machine shown in Figs. l to 6, a sheet of suitable material such for example as steel or aluminum of suitable thickness, is fed into the machine until the leading end is beyond the upper cutting member 17. While the thickness of the sheets may be varied considerably, it has been found that sheets of 18 gauge steel produce strong reticulated sheets capable of supporting heavy weights. The gauge of the sheet will depend largely upon its intended use.

With the sheet in proper position, the upper platen is operated through one cycle during which it is moved to lower position and back to its upper position, thereby forming two rows of slits and also a positioning opening 5d. The two rows of slits are the same and in the form shown containing the larger number of slits. The sheet is then advanced the proper distance until the original opening 50 is beneath the adjacent centering pin 53. In the machine illustrated, the distance of movement is equal to twice the distance between the edges of the upper cutting members 17 and 18, so that the two rows of slits first formed will be positioned on both sides of the cutting portions of the upper cutting member 16. When the upper platen is again reciprocated, two short rows of overlapping slits are cut in the sheet, in addition to two long rows of such slits. As operation of the machine continues, transverse rows of slits such as shown in Fig. 7 are formed.

The slitted portion next passes between the flattening members 25 and 26, which flatten it. Further advance of the sheet results in the upper and lower narrow punches 27 and 30a entering adjacent rows of slits and forcing the metal adjacent the slits in the direction of movement of the punches. As the sheet is further advanced the larger punches 28 and 30 enter the openingsv in the sheet formed by the narrow punches 27 and 30a and complete the rearranging of the metal to form transverse strips substantially normal to the plane of the sheet and shaped to provide substantially diamond-shaped openings therebetween. The strips are considered substantially normal to the plane of the sheet even though portions thereof may deviate 10 or 15 from the vertical or even more.

As above pointed out, after 4each advance of the sheet being processed, the upper platen 13 and associated parts pass through a cycle during which the upper platen is moved to its lower position and thereafter raised to its upper position.

During lowering of the upper platen, the hold-down bars 38 and 39 clamp the longitudinal marginal edges or portions of the sheet between these clamping bars and the supporting plates 31 and 32. Substantially simultaneously, the lingers 44 and the punches 3) and 30a also contact the upper face of the sheet in the machine. At the same time the punch 51 punches an opening 50 in the edge of the sheet and the locating pins 53 pass through the openings 50 in the sheet and into the openings 52a provided therefor in the supporting plates 31. As the lowering of the upper platen proceeds, the sheet and the supporting plates 3l and 32 are moved downwardly over the ends of the punches 27 and 23. At the same time, due to the resistance to the downward movement of the sheet, the punches 3i) and 39a enter their respective openings.

The movement of the upper platen. continues until the cooperating cutting members form transverse rows of slits in the sheets and the liattening Z5' and 26 flatten the slitted sheet therebetween. ln this position the upper and lower punches extend the maximum distance through the slits, thereby rearranging the metal to produce a reticulated sheet such as that shown in Figs 6, 8 and 9. The hold-down lingers 4d also depress the portion of the sheets therebeneath resulting in an upward slope from the two outer rows of longitudinally arranged bonds to the marginal edges of the sheet, and also counteract the upward force of the end cutters in the lower rows.

The general effect of the foregoing operation is substantially the same as if the sheet were held stationary and the upper and lower platens were moved toward each other from opposite sides of the sheet.

From the time that the clamping bars 38 and 39 engage the upper surface of the sheets supported on the supporting members 3l and 32, the margins of the sheet just outwardly of the central slirted portion are maintained substantially a fixed distance apart, and the central portion between the marginal edges, remains substantially the same size and shape. lf desired a plurality of spaced slitted portions may be formed, separated by longitudinally extending marginal portions.

it has been found advisable to maintain the marginal edges of the sheet dat during operations thereon, in which case the completed reticulated sheet will have substantially the same width and length as the original blank from which it was made. However, if desired, the marginal edges may be longitudinally bent to form depending flanges, channels etc. before being slitted and opened. Even here the surface area of the sheet would be substantially unchanged and the margins would be longitudinally straight.

It is also possible to provide a sheet having integral margins at the ends thereof, as well as at the longitudinal sides, by leaving unslitted portions at the ends.

The size of the punches employed may be varied and the number of openings in a row may also be changed. if it is desired to have a larger number of transverse openings, the upper and lower mounting plates 13 and i4 may be removed and other mounting plates containing the desired number of punches and suitable cutting members therefor may be secured to the upper and the lower platens.

ln the particular machine shown, the lower rows of punches include one more punch than the punches in the upper rows. While this is preferable, this may be reversed, in which case the hold-down lingers 44 would also be mounted on thelower platen as they are preferably adjacent to the punches in the shorter rows.

With the present machine a relatively large or a relatively small area of the sheet may be reticulated, leaving the adjacent substantially imperforate areas of any desired size.

While a particular embodiment of this invention has been illustrated and described, it will be understood, of course, that the invention is not to be limited thereto, since many modifications may be made, and it is contemplated therefore by the appended claims to cover any such modilications as fall within the true spirit and scope of this invention.

I claim:

l. Apparatus for reticulating a sheet having transverse rows of overlapping slits extending between spaced flange Y.assurs o u portions, said apparatus comprising punch supporting Vmeans, opposed sets of punches substantially diamondshaped in cross section arranged in substantially parallel transversely extending rows on said supporting means and relatively movable between open position for receiving said sheet therebetween and operative punching position with the free ends of punches of said sets overlapping, one of said sets comprising at least one row of punches with a shaping member at each end thereof movable relatively toward and away from the punches of ssi' other set for engaging portions of said sheet when the punches are in operative position, the other of said sets comprising a plurality of longer rows of punches having one more punch in each row than in said one set with the punches in said second set also aligned substantially perpendicularly to said rows of punches, said sets of punches being so arranged that when in operative position the relatively short row of punches of the one set Vlies between adjacent longer rows of punches of said other set with the punches therein offset longitudinally of said rows from said punches in the longer rows and the punches in said short row overlap the punches in the longer rows of the other set on each side thereof transversely and longitudinally of said rows.

2. The apparatus of claim l in which longitudinally extending cooperating clamping members are positioned outwardly of and adjacent to the ends of the long rows of punches and outwardly of and adjacent to the shaping members for positioning portions of said sheet engaged by said clamping members during the punching operanon.

3. The apparatus of claim l in which each of said punches tapers to a narrow edge at its free end extending generally longitudinally of said rows.

4. Apparatus for reticulating a sheet having transverse rows of overlapping slits extending between spaced flange portions, said apparatus comprising punch supporting means, opposed sets of punches substantially diamondshaped in cross section arranged in substantially parallel transversely extending rows on said supporting means and relatively movable between open position for re` ceiving said sheet therebetween and operative punching position with the free ends of the punches of said sets overlapping, one of said sets comprising a plurality of relatively short rows of punches with the punches in said set also aligned substantially perpendicularly to the rows of punches and a shaping member at each end of at least certain of said rows movable relatively toward and away from the punches of said other set for engaging portions of said sheet when said punches are in operative position, the other of said sets comprising a plurality of longer rows of punches having one more punch in each row than in said one set with the punches in said set also aligned substantially perpendicularly to said rows of punches, said sets of punches being so arranged that when in operative position the relatively short rows of punches of the one set lie between adjacent longer rows of punches of said other set with the punches in one set otset longitudinally of said rows from those in the other and the punches in a plurality of said short rows overlap the punches in a plurality of adjacent longer rows transversely and longitudinally of said rows.

5. The apparatus of claim 4 in which at least one row of punches of each set is relatively narrow as compared with the punches in other rows of said sets.

References Cited in the le of this patent UNITED STATES PATENTS 604,525 Forth May 24, 1898 668,669 White Feb. 26, 1901 875,155 Clark Dec. 31, 1907 1,059,710 Chess Apr. 22, 1913 1,090,843 Golding Mar. 24, 1914 (Other references on following page) 9 UNITED STATES PATENTS Clark July 14, 1914 Fedders Dec. 22, 1914 Gibbs Mar. 14, 1916 Bechtel Sept. 18, 1923 Ruckert Feb. 14, 1928 Frohnhauser July 17, 1928 Redding Oct. 6, 1931 Allyn Nov. 10, 1931 

